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you

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[Music]

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first off let me to mention really

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really quickly that this is actually my

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first foray into the exo astrobiology

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exoplanet habitability world and I

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really enjoyed apps icon conference so

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thanks to Apps icon for existing and

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thanks to all the people who put this on

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so I think by now we know we've heard

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enough that M dwarfs and exoplanets go

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together like peanut butter and jelly

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they really are a really nice place to

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study exoplanet science especially

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habitable zone exoplanets and we've

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heard a lot about M dwarfs so far but I

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haven't seen anyone actually put up any

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of their actual physical properties so I

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want to run through some numbers really

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quick because I think these are

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important I think some people might not

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actually know this stuff so we actually

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have M doors have masses from about half

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a solar mass all the way down to the

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hydrogen burning limit at point O eight

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solar masses they have temperatures from

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2400 to 3800 Kelvin there are more than

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anything else out there a star wise so

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none of us have actually gone outside

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and looked up and seen an AM dork before

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they're all too faint and divisible to

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actually see but there are more M doors

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than anything else

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thanks to Kepler we know that

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statistically speaking they all have

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exoplanets and a lot of these exoplanets

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that are a significant portion of them

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have earth dish sized planets in their

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habitable zone but it really is the

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physical characteristics that make the

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biggest difference in why we are so

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focused on them right so a lower mass

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means that an earth-sized planet naboo

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ozone will will induce a larger radio

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velocity signal and so that's great that

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larger signal is better for observers

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the lower temperature means lower the

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velocity and so a transiting exoplanet

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will have a deeper transit depth that's

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also great for us and the lower

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temperature also means a closer

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habitable zone so all the habitable

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zones of M dwarfs are within the orbit

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of mercury which is about point for au

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so they're very very compact systems and

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these shorter periods are great for

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detection and follow-up so if you're

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waiting for something to transit more

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than once you can wait days and weeks

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for planets in the habitable zones

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around M Dwarfs but a solar type star

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you've got to wait a year or so okay so

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this has not gone all these

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observational

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Vantage's have not gone unnoticed by

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astronomers and I won't belabor this

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because we've seen all this but we've

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made some really spectacular discoveries

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around M dwarfs recently and equally

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spectacular exoplanet artwork which is

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great for all of our talks but some of

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this I just want to point out that these

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spectral types range from M 3 4 GJ 11:32

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and 5 and a half for products an m8 for

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Travis one so we're really running the

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whole range of m-dwarf spectral types

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okay so but the real question we want to

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ask yourself is reason we're all here is

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our our habitable zone planets orbitting

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M Bors truly habitable and we've heard a

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lot from a lot of different speakers

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about how this is an extremely complex

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issue we have the tidal locking scenario

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and all the issues that that entails the

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prolonged main-sequence evolution the

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more frequent flaring which we just kind

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of talked about we had a really nice

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discussion about and increased high

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energy radiation and that's what I'm

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really focused on today okay and so one

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of the reasons that this increased

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high-energy radiation is so important

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around M courses because the habitable

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zones are so close so they're much

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closer and this really great figure put

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together by of junior school next shows

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across absorption cross-sections for a

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bunch of different molecules that we may

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be interested in and and sorry and the

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wavelength for those cross sections and

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so the best place to observe em doors to

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find out what this high-energy radiation

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would look like is in the e UV but

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unfortunately we don't have something

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that observes there at the moment what

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we do have however is Galax so Galax is

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a Galaxy Evolution Explorer what I like

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to think of also as a serendipitous

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m-dwarf Evolution Explorer so Galax had

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to UV bands the f UV and the new UV

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which are seeing here and so the idea

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behind what we're doing is we want to

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look at a whole range of spectral types

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and ages of M dwarfs and constrain

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what's going on in these this wavelength

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region and to help inform the the low

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mass models so that we can get an a

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better idea of also what

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happening over here that makes sense all

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right and so this is why the hazmat

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program was initiated hazmat stands for

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habitable zones and m-dwarf activity

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across time and so this is a really nice

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paper by shkolnik environment so this is

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one of the first results of the hazmat

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program what we're showing here is the

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flux density ratio for fuv in blue and

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near UV in white for M doors at

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different ages and so the evolution of

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the UV flux in the n UV nephew baby band

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looks something like pretty flat for the

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first few hundred million years and then

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a decrease as you get to say Heidi's age

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and then a further decrease as you get

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to field age which we're calling around

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five Giga years but this initial survey

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was done mostly with early type M and as

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we've seen in a lot of talks some of our

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most spectacular discoveries around

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later types so box 10 is an M 5.5

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Trappist m8 and so we're asking the

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question now what about late M's does

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this evolution look the same for late M

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doors and so the way we're going about

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doing this is we have we have a really

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large database of high-resolution

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optical spectra from quite a few

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different books normally quite a few

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different observatories and so we're

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looking at all the spectra finding new

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moving group members so moving groups

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are young coeval groups of stars in the

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solar neighborhood that provide an ice

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age data point for this kind of study so

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we're finding new moving group members

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and there are other groups that are also

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we're not the only ones interested in

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this for many many other reasons so

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there are other groups that are looking

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for late type M dwarfs of moving groups

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and some really nice surveys have been

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published recently like the Tyrael Hydra

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Association there was a really nice

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paper but Jonathan Gagne earlier this

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year the beta Pictoris moving group with

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an age of 24 million years this is the

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paper that's submitted at the moment it

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should be out soon

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stay tuned for that the Tuck

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association with an age of around 45

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million years there's a really nice

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survey by Adam Krauss in 2014 we're

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using the high D sample from Goldman in

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2013 so there's a really deep Heidi

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survey for low mass numbers and then for

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our older members we're using the eight

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parts example from David Kirkpatrick

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because most things in the solar

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neighborhood like really

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immediate solar neighborhood our field

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age that we can apply an older age to

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those and so this is the sample we're

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working with right now compared to the

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sample from the school neck in farming

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2014 paper and you can see for most for

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several of these groups especially kW

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Hydra beta pick in the old sample we're

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not only adding more members but we're

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also adding more later type members as

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well these are all the ones I should

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mention this these are all the ones that

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actually have a Gallic detection right

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so there are some that were observed by

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actually observed by Galax but we're not

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detected and those aren't included on

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these okay for the next few figures I'm

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actually going to break it up into two

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spectral type bins early em and later em

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and later M is going to stop at m6

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because some of these groups like tuck

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horn the hidys this basically as far out

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in spectral type range we want to get so

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we did m3 to m7 we'd be including some

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from some groups and not others so we're

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stopping at m6 just for this the

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purposes of this talk and we could break

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them up into eat individual spectral

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types but early in light kind of gets

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the point across so we have early M

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types on the left side so again this is

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the flux density ratio versus age and

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then we have lay thames over here so

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early M's you can see a similar

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unsurprisingly if we find a very similar

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trend of oracle in the environment found

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which is that it's a relatively flat for

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early ages and then you get a drop at

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heidi's age and then all the way down to

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the field age drops even further these

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red points are the medians of all these

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distributions so some of them have

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really large distributions but there are

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a lot of points underneath these medians

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so in general they're representatives of

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these groups for late type M's though

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you'll see something a little bit

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different so it looks like the the near

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UV evolution so the near UV flux is

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pretty much consistent all the way up to

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heidi's age and then drops down a little

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bit to field age and this distribution

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this spread is much larger than what we

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have over here but there are a lot of

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data points again under this spot so the

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error bars which we'll see on the next

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slide are are more representative of

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what the spread really is okay so the

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here those two distributions compared to

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each other again nothing too dramatic

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here but when you know a couple things

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to point out is that the relative change

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from from tuck or edge which is around

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45 million years to Heidi's age which is

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600 million years there's pretty much no

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change for the late MS but for the early

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ends we see a decrease and select

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density ratio of around two and a half

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times right and if you go from tuck or

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age to field age we only see a decrease

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of about three times what we would see

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at younger ages for the field age and

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for the early type M s we see a decrease

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by about eleven tile factory of eleven

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right and so this is what this is

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telling us is that the the UV flux is

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remaining at a higher level for later

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type M's for a longer period of time

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which is kind of what we expected but

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it's nice to see it in the data for okay

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for late type for late type or sorry for

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the f UV it gets a little more

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complicated so what we're actually

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seeing unfortunately is the Hyades all

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the heidi's members we searched the best

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majority of them were actually not

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detected and so only ten de Sarre

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fifteen to twenty percent of them were

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detected in the early spectral type

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range and only five to ten percent were

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detected light spectral types but we can

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say something a little bit about this

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distribution so again pretty flat I

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think I know what this is happening but

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that's a different process and they

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decreased quite a bit over here so

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unfortunately we don't have a lot of

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constraints here your guess as to what's

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going on come on buddy it's probably

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much better much much better than my

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guess as to what's going on but

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seriously we can say that the difference

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in the medians here is only for a factor

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of four but for the early type stars is

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a factor of 35 so it's even more

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dramatic for the fuv what's going on

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with these plate type stars and really

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really quickly I just want to get into

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the new UV - new UV flux ratio so we've

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heard about this in some of the earlier

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talks this week and I actually just

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stole a quote right out of Harmon 2015

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so whether Oh - and carbon monoxide can

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accumulate - appreciable concentrations

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depends on the ratio of F UV - new UV

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radiation coming from

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oink's parrots are so this ratio is

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really important for figuring out the

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chemistry and the atmospheres that are

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that are occurring on any orbiting

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planet and so what we're seeing is it's

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not only a function of spectral type

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right so this is the old spectral type

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here but it's also a function of age but

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the age is kind of interesting because

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the differences in ages are only showing

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up for the early spectral types and not

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the late spectral text right so if you

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want to figure out the fu V 2 nu V ratio

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you need to know the age and spectral

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type kind of well okay so I'll just

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leave up the summary and wait questions

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thank you thanks for the quote before

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you say anything absolutely it was my

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pleasure

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00:12:04,950 --> 00:12:03,040
Sonny Harmon Penn State I was curious if

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you have any idea so it looked like you

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didn't quite get out the lyman-alpha

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right if you have some idea of how the

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lyman-alpha is going to dominate fuv

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over those age right so you're

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absolutely right lyman-alpha will

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dominate the FPV range but i think i

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think what we're learning in a Virginia

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can correct me if I'm wrong the that fuv

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will still scale relatively right so

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your f UV 2 n UV ratio will still be

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similar whether or not you include

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lyman-alpha or not right because there

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are other lines in there there will also

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be brighter less bright Thanks no

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problem

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all right we actually also have a

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question from Ravi Kapoor he was

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watching online hi Ravi Robert why do

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00:12:49,770 --> 00:12:47,830
you lead type main sequence and UV

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00:12:53,400 --> 00:12:49,780
fluxes why don't they drop as much with

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age the main thing for late type why do

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they not drop much all right I said main

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00:12:59,400 --> 00:12:57,490
secrets why don't wait type M s & UV

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00:13:00,810 --> 00:12:59,410
fluxes why don't they drop the page yeah

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00:13:02,100 --> 00:13:00,820
so that gets into the physical reason

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00:13:05,040 --> 00:13:02,110
why this is happening which I didn't

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00:13:07,800 --> 00:13:05,050
mention at all and my guess is is that

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it's all related to rotation right so a

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so near so late type stars don't spin

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down nearly as fast what's happening is

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00:13:18,480 --> 00:13:16,510
you're basically on the edge of where

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00:13:22,020 --> 00:13:18,490
you become fully convective between m3

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and m4 and so M later M don't spin down

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00:13:25,300 --> 00:13:23,830
so they're still rapidly rotating and

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rotation related to activity

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and that's why they're just staying

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active for much longer periods of time